MUTATIONS IN PATIENTS WITH BREAST AND OVARIAN CANCER

In a study reported in the Journal of Clinical Oncology, Kurian et al found that approximately one-quarter of women with breast cancer and one-third of those with ovarian cancer underwent cancer genetic testing, and that 8% to 15% of those tested had actionable pathogenic variants.

Study Details

The population-based cohort study included women aged ≥ 20 years diagnosed with breast or ovarian cancer in California and Georgia between 2013 and 2014. These diagnoses were reported to Surveillance, Epidemiology, and End Results (SEER) registries covering the entire state populations. SEER data were linked to data from four laboratories that performed nearly all germline cancer genetic testing.

Testing and Findings

The analysis included 77,085 patients with breast cancer and 6,001 with ovarian cancer. Genetic test results were available for 24.1% of patients with breast cancer and 30.9% of those with ovarian cancer.

Among patients with breast cancer, frequency of testing decreased with increasing age at diagnosis and increasing poverty level, but did not vary markedly by race/ethnicity. Among patients with ovarian cancer, testing was lower in black patients vs white patients (21.6% vs 33.8%) and in uninsured vs insured patients (20.8% vs 35.3%).

Pathogenic variants identified in patients with breast cancer were BRCA1 (3.2%), BRCA2 (3.1%), CHEK2 (1.6%), PALB2 (1.0%), ATM (0.7%), and NBN (0.4%). Prevalent pathogenic variants in patients with ovarian cancer were BRCA1(8.7%), BRCA2 (5.8%), CHEK2 (1.4%), BRIP1 (0.9%), MSH2 (0.8%), and ATM(0.6%). Racial/ethnic differences in pathogenic variants included BRCA1 in ovarian cancer (7.2% in white patients vs 16.1% in Hispanic patients) and CHEK2in breast cancer (2.3% in white patients vs 0.1% in black patients). Testing for all genes associated with their cancer type on current guidelines showed that 7.8% of patients with breast cancer and 14.5% of those with ovarian cancer had actionable pathogenic variants.

The investigators concluded, “Clinically tested patients with breast and ovarian cancer in two large, diverse states had 8% to 15% prevalence of actionable pathogenic variants. Substantial testing gaps and disparities among patients with ovarian cancer are targets for improvement.”